There is an ongoing policy debate among competition authorities on the scope of the fair share requirement under Article 101(3) TFEU in the context of sustainability agreements. This is relevant to the review of the European Commission’s horizontal guidelines. This raises a number of important questions: Can benefits in markets different from those where the harm is identified be considered? If so, is this only the case if the consumers on the two markets are essentially the same? Is full compensation of those consumers who are negatively affected by the sustainability agreement required? In its memo the ACM analyses the MasterCard (2014) and GlaxoSmithKline (2009) line of case law. It concludes that (i) out-of-market benefits are counted towards compensation of the consumers negatively affected, in particular if they affect substantially the same group; (ii) out-of-market efficiencies benefiting other consumers can also be counted toward a fair share for consumers overall; and (iii) full compensation of the negatively affected consumers is not required, just conferral of appreciable objective advantages.